The present invention relates generally to backup pads for use with abrasive articles, and more particularly to backup pads having a quick-release mechanism.
It has long been known to use a backup pad to support abrasive articles, such as abrasive sheets which may be converted into any form, such as circular discs. The backup pad may be a hand-held pad for manual operation, or a backup pad for use with a power tool, such as a rotary or orbital sander. When the backup pad is for use on a rotary power tool, it is necessary to mount the backup pad to the rotary tool in a secure manner to prevent relative rotation between the backup pad and the power tool drive shaft. Typically, the backup pad is bolted to or is threaded engagement with the drive shaft on the power tool. (See for example, U.S. Pat. No. 3,562,968.) Other arrangements for securing the backup pad to the drive shaft of the rotary tool have also been used. (See for example, U.S. Pat. No. 3,270,467.)
However, it is seen that there exists a need for a backup pad that can be mounted securely to a drive shaft so as to prevent relative rotation between the two, and that may be easily released without the use of additional tools.
One aspect of the present invention presents a backup pad for releasably engaging an abrasive article. The backup pad comprises a body having a front surface and a back surface, releasable engagement means provided on the front surface for releasably engaging an abrasive article, and a mounting boss provided on the rear surface. The mounting boss includes a first end facing away from the body and an opening in the first end of the boss. The opening is formed by an inner surface generally perpendicular to the body and defining a non-circular cross section. The opening includes elastic means for releasably engaging a drive shaft mounted in the opening. The inner surface of the opening may a polygonal cross section, a regular polygonal cross section, or a hexagonal cross-section.
The elastic engaging means in the opening may comprise an elastic ring retained in a groove in the inner surface. The elastic ring may be, for example, an o-ring or a snap ring.
The releasable engagement means may comprise a vinyl surface adapted for releasable engagement with an adhesive layer on an abrasive article, a plurality of hooking stems adapted for releasable engagement with a loop material on an abrasive article, or a loop material adapted for releasable engagement with a plurality of hooking stems on an abrasive article.
The present invention also provides a quick release system for releasably attaching a backup pad on a mounting shaft. The system comprises a backup pad and a mounting shaft. The backup pad is as described above. The mounting shaft includes a first end and a second end. The first end includes a groove for engagement with the drastic means. The mounting shaft also includes a mating portion defining a cross section corresponding to the opening cross section in the boss.
The present invention also provides a method of refining a surface of an object with a plurality of abrasive articles. The method comprises the steps of: a) refining the surface with a first abrasive article supported on a first backup pad, the first backup pad being releasably mounted on a power tool; b) removing the first backup pad from the power tool; c) mounting a second backup pad on the power tool, with a second abrasive article supported on the second backup pad; and d) further refining the surface with the second backup pad and second abrasive article. The first abrasive article may have a composition different from the second abrasive article. The first and second backup pads preferably are mounted to the power tool by the quick release system described above.